1. Field of the Invention
The present invention relates to an electronic antitheft device for a motor vehicle having conventional functional elements allowing the control of the operation of the vehicle, namely for example an electric battery for the general electric power supply of the vehicle, an electric starter and brakes.
2. Details of the Related Art
In view of the increase in the number of thefts of motor vehicles in the last few years many antitheft devices have been developed and put on the market.
Thus, antitheft devices are known in the art which act mechanically on a control element of the vehicle, for example its steering wheel or its clutch pedal.
There are also known from document FR-A-2 569 641 safety devices preventing the unauthorized use of a vehicle which are in the form of a key cooperating on one hand with a door lock, and, on the other hand, with a key hole located on the dashboard of the vehicle. The key combines the conventional door lock opening or closing functions or the actuation of a starter, with an electronic function for opening or closing an electric switch controlling an operational system of the ignition type.
Notwithstanding the fact that the last-mentioned device is a distinct improvement over solely mechanical antitheft devices, a number of drawbacks remain, in particular the fact that this antitheft device cannot be actuated by a remote control, and that the coding does not make a distinction between the opening of the doors and the actuation of the functional elements of the vehicle and concerns a small number of bits which may be detected by scanning. Moreover, this antitheft device has no means for signalling a vehicle which might have been stolen notwithstanding the presence of the antitheft device.
Owing to the insufficiencies of the known antitheft devices, the number of vehicles stolen per year is more than 300,000 in France alone, with similar figures in other countries.
In view of this state of the art, an object of the invention is to provide an antitheft device for a motor vehicle which remedies all the drawbacks of known devices.
In particular, an object of the invention is to provide an electronic antitheft device which acts in a distinct manner on a plurality of components essential to the operation of the vehicle, while being easy to use and permitting its activation and deactivation by a mere pressing of keys of a remote control box.
A further object of the invention is to provide an antitheft device which achieves an antitheft effectiveness never achieved up to the present time while permitting an easy location of a vehicle so equipped if the latter is nonetheless stolen.
The invention therefore provides an electronic antitheft device for a motor vehicle provided with conventional functional elements allowing the control of the operation of the vehicle, namely for example an electric battery for the general electric power supply of the vehicle, an electric starter and brakes, characterized in that it comprises:
a remote control box for transmitting a digital code carried in particular by an infrared beam, said remote control box cooperating with a receptacle disposed in the driving compartment of the vehicle so that said digital code is only transmitted if the remote control box is disposed in the receptacle; PA1 an electronic centre comprising on the input side means for receiving said digital code, and connected on the output side to one or more of said functional elements so as to control their operation in the case of the reception of said digital code. PA1 said receptacle comprises means for closing an electric switch of the remote control box upon the positioning of said remote control box in said receptacle, said electric switch being disposed in the electric circuits of the remote control box so as to prevent the transmission of said digital code so long as said electric switch is open; PA1 said means for closing an electric switch are constituted by a magnetic device, for example a permanent magnet disposed in proximity to the receptacle, for example under the base of the latter, and said electric switch is an electromagnetic switch which is closed under the effect of said magnetic device when the remote control box is positioned in the receptacle; PA1 said remote control box comprises infrared means for transmitting said digital code by actuation of a group of contact keys disposed on said box, one of said contact keys causing the actuation of a first functional element of the vehicle, for example the locking/unlocking of the doors of the vehicle by transmission and decoding of said digital code, and the actuation of at least one of the other keys causing the actuation of a plurality of other functional elements of the vehicle as soon as said mobile remote control box is disposed in said receptacle; PA1 the remote control box is positioned in the receptacle in such manner that said infrared transmitting means are in direct view of said receiving means; PA1 the antitheft device comprises means for reflecting the infrared beam transmitted by the remote control box, said reflecting means ensuring the reflection of the infrared beam in a multitude of paths, and said receiving means being disposed at the intersection of any one of said paths for indirectly receiving the transmitted beam; PA1 said reflecting means are constituted by a cylindrical reflecting billet disposed on the receptacle in direct view of the infrared beam transmitted by the remote control box; PA1 a digital code is transmitted upon the actuation of any contact key of said box, said code comprising a first group of secret identification bits personalized for a given electronic antitheft device, and a second group of actuating bits representing the particular contact key actuated and corresponding to one or more particular functional elements of the vehicle; PA1 said electronic centre comprises means for fixing a predetermined sequence of actuation of the functional elements of the vehicle, and means for comparing the order of actuation of the contact keys of the box with said predetermined sequence, said functional elements being actuated by the centre solely if the order of actuation of the keys corresponds to the predetermined sequence; PA1 the other keys cause the actuation of electronic circuits controlling the release of the brakes of the vehicle, circuits controlling the closure of the general electrical circuit of the vehicle, circuits controlling the starter of the vehicle, or circuits controlling the opening of a fuel electrovalve; PA1 said electronic centre comprises: PA1 the electronic antitheft device further comprises:
According to other features of the invention:
a circuit for receiving and preamplifying the infrared beam, which drives circuits for decoding the access code transmitted by the remote control box; PA2 a circuit for storing a personalized identification code assigned to the considered antitheft device; PA2 comparison means connected to said decoding circuit and to said storage circuit for comparing said personalized code with that recorded in said storage circuit and only allowing the sequence of subsequent control operations of the electronic antitheft device in the case of coincidence of said comparison; PA2 flip-flop circuits generating actuating control signals when said comparison is positive, said actuating control signals being transmitted to the corresponding functional elements of the vehicle through the medium of electric relays disposed in the power supply circuits of said functional elements; PA2 said circuits for storing the access code comprise first logic circuits having shift registers disposed in a ring arrangement, and said decoding circuits comprise second logic circuits having shift registers for decoding actuating bits of the functional elements, the decoding of identification bits only being authorized if the correct access code has been decoded; PA2 a radio beacon placed in said vehicle and provided with means for causing the transmission of the beacon in the case of a forced intrusion into the vehicle, for example by a forced opening of the doors, of the luggage compartment or of the engine hood of the vehicle or by the raising of the vehicle; PA2 means placed in said remote control box for neutralizing the operation of said radio beacon when transmitting a control signal for opening the doors, for example by the use of a mercury switch; PA2 said beacon further comprises radio receiving circuits, the signal transmitted or received employing a carrier wave whose frequency is within a frequency range used by road control organizations so as to facilitate the location by the latter of a stolen vehicle.